Kate and William were pictured at Bedford House, on a two-day visit to Belgium and will later join Prince Charles and Prime Minister Theresa May for a ceremony to remember those killed in the notorious First World War campaign.

The couple walked among graves at the Tyne Cot cemetery, the biggest Commonwealth burial ground in the world, with more than 5,140 WWI servicemen and nearly 70 WW2 servicemen are buried.

During their visit Kate - wearing a Catherine Walker lace coat with a red poppy pinned on the lapel - was pictured speaking with interns from the Commonwealth War Graves Commission, who tirelessly work to keep the soldiers' stories alive.

The couple were then given a tour of graves by the commission's director Victoria Wallace on the centenary of Passchendaele - also known as The Third Battle of Ypres.

They are set to be joined by The Prince of Wales, later, as he officially opens the Zonnebeke Church Dugout, a preserved First World War dugout which forms part of the Memorial Museum Passchendaele.

He will then open the nearby British Memorial Poppy Garden in Passchendaele Memorial Park, where the royals will meet designers and gardeners who look after the grounds.

The Prince of Wales will then join hundreds of guests at the Exhibition Field at The Passchendaele Memorial Park to meet families and descendants of those who fought and fell at Passchendaele, as well as school children learning about the history of the battle.

Kate and Wills happily chat together as they walk through the cemetery (Image: PA)

His Royal Highness will then go on to the Welsh National Service of Remembrance at the Welsh National Memorial Park to mark the centenary of Passchendaele and the Welsh soldiers who lost their lives in the battle.

Following the service, The Prince of Wales will visit Artillery Wood Cemetery.

His Royal Highness will tour the cemetery, which includes the graves of poets Hedd Wyn and Francis Ledwidge, both killed during the Battle of Passchendaele.

Yesterday William spoke at the Menin Gate monument in Ypres, Belgium, as the daily Last Post was played ahead of today's commemorations.

Flanked by the Duchess of Cambridge and Philippe and Mathilde, the King and Queen of the Belgians, he said Britain and Belgium "stand together" to remember those killed during weeks of heavy fighting in the summer and autumn of 1917.

Bedford House is the final resting place of more than 5,140 servicemen of the First World War and nearly 70 servicemen of the Second World War (Image: PA)

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They watched as thousands of paper poppy petals, one for every name on the Menin Gate, fluttered to earth from the roof above the gathered crowd.

Four thousand people were chosen by a ballot to attend events in Ypres today and the larger event centred on nearby Tyne Cot military cemetery on Monday.

Sunday's poignant Last Post was the 30,752nd time it has been played since 1928.

The towering Menin Gate in the Belgian town is covered with the names of 54,391 British dead who have no known grave, according to the Commonwealth War Graves Commission.

In just over three months of conflict there were more than half a million casualties - 325,000 Allied soldiers and 260,000 to 400,000 Germans - in the Belgian battlefields.

Theresa May all smiles as she arrives at the Menin Gate in Ypres (Image: PA)

It was fought between July 31 and November 10 1917 in battlefields that were summed up in poet Siegfried Sassoon's line "I died in hell, they called it Passchendaele".

Those who fought there included Harry Patch, the "Last Tommy" who died aged 111 in 2009.

While powerful testimony featured the stories and voices of the soldiers who fought at Passchendaele. Scottish-born Andrew Bowie was 19 when he fought, and was filmed by a historian before he died.

He recalled: “I was no hero. We were there to take Passchendaele ridge. You could tell there was anxiety in the air, what was going to happen after daylight tomorrow.

(Image: Daily Mirror)

“When I came to attack, hell was let loose by the Germans because they were on the ridge and we were in the flat below.

“They couldn't miss with their machine guns. I didn't get very far, none of us got far, we just stopped.We just couldn't go, the fire was so intense they just blasted us off the earth

“It was just a bloody massacre. We were in the shell hole for two or three days – we couldn't see a way out. This place was being sprayed with machine gun”.

He told how he and another soldier escaped by pretending we were stretcher bearers and that was the “great escape for us”.

“I felt like it was just a waste of human life," he added.

What was the Battle of Passchendaele?

The Third Battle of Ypres, known as Passchendaele, began in the early hours of July 31, 1917.

It's primary objective was to dislodge German forces from the high ground around the city of Ypres (now Ieper) and then advance to Belgian coastal ports from where German U-boats threatened Allied shipping.

Men from virtually every corner of Britain’s then Empire took part. They faced well-established enemy defences and heavy rain that turned the battlefields into a muddy quagmire.

The conditions at Passchendaele are among the most enduring images of the First World War. The offensive ended after the capture of Passchendaele village by Canadian forces on 10th November.

By the battle’s end, the Allied forces had advanced a mere 8 kilometres. The human cost was appalling – an estimated 500,000 men on both sides had been killed, wounded, were captured or missing.